peterson



Dec. 16, 1941. T. F. PETERSQN R. 21,979- Y HEATING n svxcs OriginalFiled Dec. 9, 137 2 Sheets-Sheet l INVENTOR; 77200245 FFZIZ/So r W2- YATTORNEY.

' Dec. 16, 1941. T. F. PETERSON HEATING nsvrcs 2 Sheets-Sheet 2 OriginalFiled 085. 9, 19:57

INVENTOR.

m. M H a. M

/ ATTORNEY.

Reisaued Dec. 16, 1941 UNITED STATES PATENT OFFICE 21,979 V HEATINGDEVICE Thomas F. Peterson, Worcester, Mass. Original No. 2,156,352,dated May 2, 1939, Serial No. 178,876, December 9, 1937. Application forreissue February 10, 1940, Serial No. 318,377

g 8 Claims. This invention relates to heaters and methods of heating,more particularly designed for the baking or heating of longitudinalelements as wires, rods, cables or the like. The customary practice fortreating such elements is to wind them on reels or in coils and placethem in an oven, as for example in the annealing of wire, curingrubber-coated elements, drying cable, etc. Sometimes the elements arepassed through chambers heated by gas, oil, coal, hot air or steam. Whenthe elements are of metal, induction heating or resistance heating bythe passage of an electric current may bev used. All these methods,however, are objectionable either fromthe lack of efiiciency or the lackof uniformity in the heat treatment.

The present invention provides a method of radiant heating or treatingwith other forms of radiant energy exteriorly, and apparatus therefor,that operates with efliciency and uniformity. It furthermore providesfor exact control of the change or reaction caused by the radiantenergy.

Moreover, by heating or applying radiant energy exteriorly under closelycontrolled conditions in accordance with thisinvention, it is found thatthe amount of heating or radiant energy required for baking, vulcanizingand other similar operations involving a physicai or chemical change, e.g. a heat-reaction, in the surface or in the surfacing material on theelement being treated, can be applied without unduly creating changessuch as raising the temperature of the interior. For instance in someforms of rubberjacketed cable, insulation is present in the interior ofthe cable'that deteriorates if exposed to g the temperature required forrubber vulcanization; the present invention permits the manuregion. Asan instance the embodiment (here inafter more fully described) can bethat of a cylinder of elliptical right section with the element to betreated extending through the locus of one a: the foci of the ellipse;in this case,

the source of the energy, such as an electric resistance wire, can bepositioned along the locus of the conjugate focus.

There are practical limitations imposed on structural embodiments of theinvention. To be operative in a commercial sense it is essential that amajor part at least of the emitted energy be concentrated or condensedwithin a focal area or region corresponding to and not much less than across-section of the element being treated, and vice versa that theelement being treated have a cross-section approximating or exceedingthe focal area into which the waves are condensed in order to interceptto a useful extent the radiant energy; otherwise the variableness inwave propagation, wastage of energy and consequent cost of operationnullify the advantages to be had over direct energy application.

tion, permissible waste, etc., all of which have facture of such cablewithout injuryto the heatsensitive interior insulation. Similarly in thebaking of enamel coatings it is at times desirable that a relativelyhigh temperature be employed for obtaining a hard resistant coatingwithout creating objectionable changes in plasticity or other propertiesof insulation under the "coating.

In general the objects of the present invention are accomplished by thecondensation of reflected heat or other radiant energy waves, in placeof or in conjunction with other forms of energy, upon the element beingtreated. A practical embodiment is that or a closed cylindrical ovenwith an interior reflecting surface and having a focal region withinwhich the reflected energy waves such as heat waves can be condensed;the wire, cable or other longitudinal element is positioned or movedthrough the focal their modifying effects because of these many factorsthe minimum focal area or cross-section of the material treated cannotbe expressed by any formula or in any definite, terms. It may be stated,however, that elements of the sizes and material of textile threads arenot within the category of elements contemplated for treatment inaccordance with this invention or found amenable in practice to suchtreatment. Elements to which the present invention is applicable arewires, rods, cables and built-up structures sufficient in cross-sectionto subtend the major part at least of the waves condensed at the focalarea and furthermore of a nature. or material that involves somealteration in a physical or chemical sense and that is capable ofsubjection to the action of the radiant waves when concentrated withoutobjectionably injurious effeet. In the absence of any means ofmeasurement or classification as to material the elements to which thisinvention apply are deilned as of appreciable cross-section and ofmaterials susceptible to radiant energy reaction. a In the accompanyingdrawings:

Fig. l is an elevation of an assembly illustrating an embodiment of thepresent invention;

Fig. 2 illustrates an enlarged right section on the line 2-2 of Fig. 1;and

Fig. 3 illustrates another form of right section for the heater.

The heater. or oven I is illustrated as a vertical tower or cylindersuitably supported from the floors II and I2; the length of the towercan radiant waves are condensed. The bushings in the closed ends of thetower can be of refractory material as porcelain or the like; and thebushplaced to properly position the element I4, such as wire to beannealed or baked, as it is drawn from the reel l5. At the upper end ofthe tower there is mounted a second guiding sheave it which can beoperated from a motor and suitable transmission gearing in housing I!for drawin the wire through the heating tower. Before passing over thedriving sheave 18 it may be desirable to cool the wire as it comes fromthe heating tower by means of a current of air created by a fan ll.Or'as the wire leaves the driving sheave, it can be passed downwardlythrough a cooling tower I 9 before being drawn onto the spool 20 overthe guiding sheave 2|. These parts are of course subject to change andsubstitution, depending upon the use made of the tower; for instancewhen wire is to be coated and then baked, the sheave I: can be placed ina tank or tray containing the coating material to guide and submerge thewire in the coating material. As another instance the cooling tower l9can be built similarly to the heating, tower in whereby the heat givenoil by the wire on cooling can be utilized as a preliminary heatingmeans for another wire or a different portion of the same wire. V

The heating tower as illustrated in Fig. 2 has as its right section anellipse. The metal wall 7 sun provided with an interior-reflectingsurface 3I. The metal wall can be made in sections 32, 33 with angles34, 35 welded thereto and bolted together by bolts 38. An insulatingjacket 31 of asbestos or the like is placed about permit operationsunder pressure if desired.

When so closed at both ends the tower can be ventilated by providingsuitable iniets'and outlets] for the circulation of a gaseous medium:when a coating is being baked, the solvent vapors drawn through anoutlet can be suitably condensed.

The element or wire it to be heat-treated is passed through a bushing inthe base 3! when the tower is closed. The bushing is located at a focusof the elliptical cross-section. There can be a similarbushing locatedat the focus atthe upper end, and if found necessary additional guidesof porcelain or the like along the length of the tower can be provided.The purings can be longitudinally extended from the ends of the tower togive a gradual cooling of ing element. Thiscan conveniently be anelectrical resistance element in the form of a rod with suitableconnections for current, or it may be a gas-fired hollow tube. The heatrays thrown oil by the heating element lll strike the reflecting innersurface of the tower as shown by the lines ll and are reflected withinthe focal area II.

In Fig. 3 there is illustrated in cross-section another embodiment. Inthis form the right section 50 is parabolic with the wire to be treatedat the focus ii. To providea closed tower two parabolic walls 52 and 53secured together by bolts 54 are provided and. having the common focus5|. Heat is provided by plates 5|, 8| placed perpendicularly to the axisof the. parabola and on a line through the focus: the parallel heat rays51 are therebyreflected back of the wall and condensed within the focalregion 5i. The plates may be any convenient form of heating means, forinstance, they can be built up' comprise two parabolic walls .as shown.One can be omitted and a heating plate used as a part of the cylindricalwall; in this case, the heating plate is preferably placed a distancebeyond the focal line such as to equalize as nearly as possible theheating effect on all sides of the being treated.

The operation of the heating device is believed obvious from theforegoing description. The wire, cable or other longitudinal element tobe annealed, baked, vulcanized or otherwise heattreat'ed is maintainedinthe focal area of the cylindrical tower as determined by the rightsection of the tower within which the waves are condensed. The elementis drawn through the tower at a rate of speed depending upon the timeperiod of heating, the degree of heat condensed upon the element and theheight of the element tower. Evidently these factors can be accuratelycontrolled to give Just the amount of heating necessary for eachparticular operation. Because of the controlled heating so obtained ithas been found possible to vulcanize a rubber Jacket or covering over aheat-sensitive insulation without injury to the insulation.

'The tower is primarily intended for the heating of continuouselementsas wire and the like to be drawn through the tower. 'It is possible. ofcourse, to support an element in a stationary position along the locusof a focus and flash on the heat for a length voi time necessary tosecure the eflect desired. The element after treatment is thendismounted.

What is claimed is:

1. A heating device comprising in combination a cylindrical tower havinga right section of a curvature providing a focal area and having aninterior reflective'surface, said tower being provided with cloud ends,means associated with the tower for maintaining a material to beheatplates are suitably supported corresponding to treated along thefocal region of the tower, said supporting means permitting movement ofthe material along the tower, refractory bushings mounted in the ends ofthe tower and along the focal region of the tower. for permittingmovement of the material while substantially sealing the interior of thetower to render the tower capable of operation under presence of aninert atmosphere, and heating means having its heating surfacepositioned in the tower so that heat waves radiating therefrom arereflected from the reflective surface and condensed upon the focalregion of the tower.

2. Radiant energy transmitting device for causing changes in materialscomprising in combination a tower having a wall with a right section ofa curvature providing a focal area'and with a straight line generatrix,said wall having a reflecting surface to substantially condense radiatedenergy waves within the focal region of the wall upon a matepressure or.in the.

. tudinally of the focal rial when of a cross-section substantiallycorresponding to or greater than the focal area and extendinglongitudinally of the focal region of the tower, and a source of energypositioned in the tower so that energy waves radiated therefrom arereflected by the reflecting surface and condensed upon the focal regionof the tower, said energy source being constituted by an elementextending in parallelism to the wall generatrixand of a size emittingsufficient energy to cause the desired change in the material treated.

8. Radiant energy transmitting device for causing changes in materialscomprising in combination a tower having a wall with a right sectioncorresponding to a parabola providing a focal area and with a straightline generatrix, said wall having a reflecting surface to substantiallycondense radiated energy waves within the focal cross-sectionsubstantially corresponding to or greater than the focal area andextending longiregion of the tower, and a source of energy positioned inthe tower so that energy waves radiated therefrom are reflected by thereflecting surface and condensed upon the focal region of the tower,said energy source being constituted by an elementv extending inparallelism to the wall generatrix and of asize emitting suflicientenergy ing walls parabolic in cross-section with a common focal regionand havinga reflecting surface to substantially condense radiated energywaves within the focal region, and a source of'radiant energy positionedwithin the towerso that energy waves radiated therefrom are reflected bythe reflecting surface and condensed upon the focal region of the tower.

6. Heating device for causing changes in ma terials comprising incombination a tower constituted by longitudinally extending wallsparabolic in cross-section with a common focal region and having areflecting surface to substantially condense radiated energy waveswithin the focal region, and a source of radiant heat energy positionedwithin the tower so that energy waves radiated therefrom are reflectedby the reflectin surface and condensed upon the focal region of thetower.

'1. Process of imparting energy by radiation for causing changes inmaterials which comprises region of the wall upon'a material when of across-section substantially corresponding to or greater than the focalarea and extending longitudinally of the focal region of the tower, anda source of energy positioned in the tower so that energy waves radiatedtherefrom are reflected by the reflecting surface and condensed upon thefocal region of the tower, said energy source being constituted by anelement extending in parallelism to the wall generatrix and of a sizeemitting sufflcient energy to cause in the material treated.

4. Radiant energy transmitting device for causing changes in materialscomprising in combination a tower having a an ellipse providing a focalarea and with a straight line generatrix, said wall the desired change 1wallwith a right section I providing a longitudinally extendingreflecting surface having a focal region and imposing on the reflectingsurface energy waves emanating from a radiating source for condensationupon a material of a cross-section substantially corresponding to orgreater than the focal area and extending longitudinally of the focalregion.

8. Process of heating by radiation for causing changes in materialswhich comprises providing a longitudinally extending reflecting surfacehaving a focal region and imposing on the reflecting surface heat wavesemanating from a heat radiating source for condensation upon a materialof a cross-section substantially corresponding to or greater than thefocal area andextending longitudinally of the focal region.

- THO MAB r. PETERSON.

to cause the desired change in the material treated.

